DIRECT MICROMECHANICAL SIMULATIONS FOR DAMAGE ACCUMULATION IN COMPOSITE MATERIALS

RESEARCHERS ARE DEVELOPING DIRECT MICROMECHANICAL SIMULATION TECHNIQUE TO MODEL DAMAGE ACCUMULATION IN COMPOSITE MATERIALS. COMPOSITE MATERIAL TECHNOLOGY ALLOWS THE ENGINEER TO TAILOR THE MATERIAL PROPERTIES FOR THE SPECIFIC DESIGN REQUIREMENTS OF A MECHANICAL SYSTEM, SUCH AS A PROPULSION SYSTEM. THIS UNIQUE ASPECT OF COMPOSITE MATERIALS OVERLAPS THE ROLES OF THE DESIGN ENGINEER AND THE MATERIAL SCIENTIST AND REQUIRES AN UNDERSTANDING OF HOW COMPOSITE CONSTITUENTS INTERACT TO PROVIDE THE DESIRED MATERIAL PROPERTISE NEEDED FOR THE STRUCTURE DESIGN. THIS PROJECT ADDRESSES A NEED FOR A "BRIDGING" TECHNOLOGY; A BROAD ANALYTICAL TOOL TO EVALUATE COMPOSITE MATERIAL DEFORMATION, FRACTURE, DAMAGE ACCUMULATION, AND FAILURE BASED ON THE UNDERLYING MICROSTRUCTURAL DEFECTS AND THE EVOLUTION OF THE MICROSTRUCTURAL STATE UNDER MULTIAXIAL LOADING. THE CURRENT CAPABILITIES OF MISTRA (TM), A WINDOWS-BASED FINITE ELEMENT ANALYSIS CODE DESIGNED SPECIFICALLY FOR MICROSTRUCTURAL ANALYSIS ARE BEING EXPLORED. RESEARCHERS ARE INVESTIGATING GRID GENERATORS, SOLUTION ALGORITHMS, AND VISUALIZATION TECHNIQUES FOR ANALYZING THE GROWTH IN DAMAGE OF AN INITIAL DISTRIBUTION OF MICROCRACKS UNDER THERMAL AND STRESS LOADS. DIRECT MICROMECHANICAL SIMULATION IS ANALOGOUS TO DIRECT NUMERICAL SIMULATIONS USED TO STUDY TURBULENT FLOW FIELDS. THESE MICROMECHANICAL SIMULATIONS ESTABLISH A DIRECT RELATIONSHIP BETWEEN THE EVOLUTION OF THE MICRODAMAGE ACCUMULATION AND THE LOSS OF LOAD-CARRYING CAPABILITY OF THE BULK COMPOSITE MATERIAL. THIS INNOVATIVE APPROACH ALLOWS THE DESIGN ENGINEER TO ASCERTAIN THE EFFECTS OF THE MICROSCOPIC MATERIAL DESIGN AND PROCESSING ON THE ULTIMATE DESIGN OF THE COMPOSITE STRUCTURE AS A WHOLE.